Dryer

ABSTRACT

Apparatus for drying moist solid material, of the type utilizing disc heat exchange elements into which a heating fluid is introduced and cooled fluid is withdrawn, the material being dried through contact with a plurality of discs in its passage through the apparatus. The present apparatus is characterized by torus discs formed from relatively thin-walled circular metal plates for good heat transfer to the material and having a plurality of concentric rings of convex arcuate cross section for strength. The disc encloses a plurality of interconnected concentric generally toroidal chambers through which heating fluid, such as steam, is circulated successively and from the outermost of which cooled fluid, such as condensate, is withdrawn.

United States Patent 1 Phillips Dec. 11, 1973 DRYER [75] Inventor: David L. Phillips, Fridley, Minn.

[73] Assignee: The Strong-Scott Mfg. Co.,

Minneapolis, Minn.

[22] Filed: Aug. 24, 1972 [21] Appl. No.: 283,387

[52] US. Cl 165/92, 34/124, 34/179, 34/183 [51] Int. Cl. F28f [58] Field of Search 165/92; 34/124, 125, 34/140,141,l42,179,183

[56] References Cited UNITED STATES PATENTS 3,563,710 2/1971 Dew, Jr. et a1. 165/92 FOREIGN PATENTS OR APPLICATIONS 789,439 1/1958 Great Britain 165/92 811,020 4/1969 Canada 165/92 Primary Examiner-Carroll B. Dority, Jr. Assistant Examiner-Larry l. Schwartz Attorney-L. Paul Burd et a1.

[57] ABSTRACT Apparatus for drying moist solid material, of the type utilizing disc heat exchange elements into which a heating fluid is introduced and cooled fluid is withdrawn, the material being dried through contact with a plurality of discs in its passage through the apparatus.

The present apparatus is characterized by torus discs formed from relatively thin-walled circular metal plates for good heat transfer to the material and having a plurality of concentric rings of convex arcuate cross section for strength. The disc encloses a plurality of interconnected concentric generally toroidal chambers through which heating fluid, such as steam, is circulated successively and from the outermost of which cooled fluid, such as condensate, is withdrawn.

11 Claims, 3 Drawing Figures PAIENIED i sum 1 BF 3 .Fzcal DRYER This invention is directed to a drying apparatus of the I the present apparatus is the type in which the rotor ineludes disc heating elements through which a heating fluid circulates. The present apparatus is characterized by torus discs of thinwalled heat conducting metal for good transfer of heat, the discs being formed from circular plates having a plurality of concentric rings of convex arcuate cross section for strength and maximum heat conducting surface.

The invention is illustrated by the accompanying drawings in which:

FIG. 1 is a side elevation of the dryer of the present invention shown partly broken away to reveal internal structure;

FIG. 2 is a fragmentary elevation partly in section and partly broken 'away showing details of structure of the dryer rotor; and

FIG. 3 is a vertical section on an enlarged scale of a cross sectional view of the present invention.

Referring to the drawings, the apparatus comprises a horizontally disposed housing of circular or oval or U-shaped cross section supported at one end by a pair of legs 11 and cradled adjacent the opposite end in a saddle 12. A shaft, indicated generally at 13, extends,

lengthwise through the end walls of. the housing, being provided with suitable sealsand journaled forrot ation on a horizontal axis in bearings 14 and 15. The bearings are mounted outside of the opposite end walls of the housing on cross beams 16 and 17, respectively, supported between gussets l8 and 19, respectively. A drive sprocket 20 is secured to one end of shaft 13.

The illustrated form of housing, having a generally U-shaped cross section, is provided with a flat cover.21. A material inlet 22 to the housing is provided adjacent one end thereof. A vapor exhaust 23 from the housing is provided at the other end. One or more covered access ports 24 are desirably provided in cover 21. Housing 10 is desirablydouble-walled over at least part of its surface being provided with a jacket 25 having at least two headers 26 and 27 for introduction and discharge of a heating fluid, such as steam, to the narrow space between the housing wall and jacket wall. A discharge weir 28 communicates through the end wall of the housing with the drying chamber for removal of dried material.

Rotor shaft 13 includes an outer tube 30 and inner concentric tube 31. The annular space between tubes 30 and 31 is a conduit 32 for passageof heating fluid such as steam to each of a plurality of disc heating elements, indicated generally at 33, carried by the shaft. The space 34 within tube 31 serves as a conduit for return passage of cooled fluid, such as condensate, from discs 33. Outer tube 30 is provided with a plurality of ports 35 corresponding in number to the number of discs 33 mounted on the shaft. Ports 35 for alternate discs are desirably disposed on opposite sides of tube 30. Tubes 30 and 31 are each provided with ports 36 and 37, respectively, in registry to receive a condensate return tube 38. Ports 36 are present in number corresponding to the number of discs 33 and are disposed on opposite sides of tube 30 from ports 35 and alternating ports 36 are disposed on opposite sides of the tube. Tube 38 preferably extends radially inwardly to at least the longitudinal axis of tube 31 to prevent backflow of condensate into the discs as the rotor turns.

Each disc heating element includes a hub 40 having a pair of ports 41 and 42 which are in registry with ports 35 and 36 when hub 40 is brazed or otherwise mounted on tube 30. Hub 40 is provided 'with a pair of spaced apart backup rings 43 welded or other-wise secured to the outer perimeter of the hub on opposite sides of ports 41 and 42. A pair of facing circular rotor torus plates, indicated generally at 44, make up the outer walls of the discs 33. Each rotor torus is composed of a plurality of concentric rings 45, 46 of convex arcuate cross section. The inner peripheries of torus plates 44 are welded or otherwise secured to backup rings 43 and hub 40. The outer edge of each rotor torus is a flange 47 welded or otherwise secured to outer disc ring 48. Convex torus rings 45 and 46 are separated by a concentric flat circular ring by which the torus plates are welded or otherwise secured to an inner disc ring 50.

Convex rings 45 of the facing pair of rotor torus plates 44, along with hub 40 and inner disc 50, enclose a generally toroidal inner chamber 51 which is in communication through ports 41 and 35 with conduit 32 in the rotor shaft for introduction of steam into the chamber. Rotor torus rings 46, along with inner ring and outer ring 48, enclose an outer generally toroidal chamber 52. Outer chamber 52 is in communication with inner chamber 51 to receive heating fluid thereform through port 53 in inner ring 50. Port 53 is dis posed generally on the opposite side of the rotor from ports 41 and 35. Although the disc heating element is shown as composed of two concentric chambers, it will be apparent that three or more similarly constructed and interconnected concentric chambers may be incorporated into the disc structure.

As the heating fluid circulates and cools as a result of heat exchange through the rotor torus walls, cooled fluid tends to accumulate in the outermost toroidal chamber 52. To facilitate removal of this cooled fluid, an arcuate tubular collector conduit 54 is disposed within chamber 52 against its outermost peripheral wall adjacent to outer disc ring 48. One end of collector conduit 54 in the direction of rotation of the rotor is open and the opposite end is connected to a tubular conduit 55 for removing collected condensate or similar cooling fluid. Remover tube 55 extends generally radially through port 36 in inner disc ring 50 and port 42 in hub 40 to communicate with radial tube 38 which extends through shaft tubes 30 and 31 to condensate return conduit 34. As the rotor is rotated, the open end of collector tube 54 functions as a scoop to gather up accumulated condensate at the outer periphery of chamber 52. The condensate is propelled the length of the collector tube into the remover tube 55 and thence into the condensate return conduit 34.

Condensate return conduit 34 terminates in a short chamber 56 at one end of the shaft. Chamber 56 is of greater diameter than inner tube 31 such that returning condensate collects in a pool in the bottom of chamber 56. A condensate return fitting 57 is journaled in bearing 58 mounted in shaft end plate 59. A vertically disposed tube 60 extends downward from fitting 57 into the bottom of chamber 56. Tube 60 is of such length that it extends beyond the outer perimeter of inner shaft tube 3 1 so that, when the dryeris in operation,'it extends into the pool of collected condensate in the bottom of chamber 56. A condensate return pipe 61 extends from the opposite end of fitting 57 through the end of the shaft for removal and discharge of the condensate. As shaft 13 rotates, fitting 57, tube 60 and pipe 61 all remain stationary being journaled in bearing 58 so that the bottom of chamber 56 functions as a trap through which the condensate is withdrawn and discharged.

To agitate the material being dried and assist transport of the material through the dryer housing, the outer peripheries of the rotor heat exchange discs are desirably provided with a plurality of paddles 62. Each paddle 62 is secured to the outer periphery of outer .disc ring 48. The paddles extend to close proximity with the inner housing wall sufficient to permit rotation with close clearance with respect to the wall. The pad dles are desirably disposed at an angle relative to the longitudinal axis of the apparatus, the precise angle being determined by the desired rate of movement of the material through the housing, rotor speed, etc. A rotor plow 63 is secured to the inside wall of the housing so as to extend between each adjacent pair of discs to just short of disc hub 40 to prevent accumulation and buildup of material between the discs. The surfaces of the discs and housing are smooth and polished to minimize adherence of material. A valve 64 is provided to facilitate cleaning, etc. of the dryer.

The torus disc heating elements in combination with the steam jacket of the drying chamber provides a good concentration of heating area per unit of volume. The thin-walled construction permitted by the novel torus design provides efficient heat exchange and increased surface area without sacrifice of disc strength. The torus disc plates 44 for a 23 inch diameter dryer, for example, are desirably formed from 14 gauge stainless steel. The design of the discs makes possible a concentration of up to 85 per cent of the total heating surface on the rotor. In addition to insuring a compact unit, this is advantageous for the drying process. The dryer is especially adapted for high heat load and long residence type drying of plastics, chemicals, foods and food byproducts.

lt is apparent that many modifications and variations of this invention as hereinbefore set forth may be made without departing from the spirit and scope thereof.

The specific embodiments described are given by way of example only and the invention is limited only by the terms of the appended claims.

The embodiments of the invention in which an exclu- Sive property or privilege is claimed are defined as follows:

1. An apparatus for drying solid materials comprising: t

A. a horizontally disposed housing having a material inlet adjacent one-end and a material discharge adjacent the other end,

B. a rotor shaft extending longitudinally through said housing journaled for rotation on a horizontal axis,- C. a plurality of hollow disc heating elements carriedon said shaft for rotation therewith within the housing, 1

D. at leat two chambers within said disc heating elements spaced'radially' outwardly from said shaft,

E. port means interconnecting adjacent chambers for pa'ssageof heating fluid,

- F. first conduitmeans within said shaft for introducing-heating fluid to said heating elements and further conduit means for withdrawing cooler fluid therefrom, and I G. means connecting the innermost of said disc chambers with said first conduit means within the shaft and means connecting the outermost of said disc chambers with said further conduit means.

2. An apparatus according to claim 1 further characterized in that each of said disc heating elements comprises:

' A. a housing having a pair of facing thin-walled circular plates having a plurality of concentric rings of convex arcuate cross section enclosing a plurality of concentric generally toroidal chambers,

B. collector means within the outermost of said chambers for collecting cooler fluid therefrom and conduit means for removing the same.

3. An apparatus according to claim 2 further characterized in that:

A. said rotor shaft includes a pair of concentric tubes,

B. the space between said tubes is a conduit for introducing heating fluid to the disc heating elements and the space within the innermost tube is a return conduit for cooler fluid,

C. ports in the outermost tube communicate with the innermost of said concentric toroidal chambers,

and

D. tubular conduits extending through the walls of both concentric tubes communicate with the fluid collecting and removing means of the outermost disc chamber.

4. An apparatus according to claim 2 further characterized in that said fluid collecting and removing means connecting the outermost of said disc chambers with said further conduit means comprises:

A. an arcuate tubular conduit disposed within the outermost toroidal chamber against the outermost peripheral wall thereof, one end of said conduit toward the direction of rotation of the disc being open, and i B. a generally radial tubular conduit connected to the opposite end of said tubular conduit and extending through the toroidal chambers to communicate with the further conduit means of the rotor shaft for the passage of fluid therethrough.

5. An apparatus according to claim 1 further characterized in that:

A. said housing is double-walled over at least part of its surface, and B. inlet and outlet means are provided in communication with the space between said walls for circulation of heating fluid therein. 6.An apparatus according to claim 1 further characterized in that:

A. said rotor shaft includes a pair of concentric tubes, B. the space between said tubes is a conduit for entry of heating fluid and the space within the innermost tube' is a return conduit for cooler fluid, C. each disc heating element comprises a hub carryi'nga'pair of facing thin-walled circular heat conducting plates, said plates having a plurality of con- "centri'c' rings of convex arcuate cross section enerasing a plurality of concentric generally toroidal chambers,

D. entry port means in the outermost tube of the rotor shaft communicate with entry port means in said hub,

E. collector means are provided within the outermost chamber for collecting cooler fluid,

F. conduit means are provided connected to said collector means for removing cooler fluid, and

G. tubular conduits extending through the walls of both concentric tubes of the rotor shaft communicate with discharge port means in said hub for removing cooler fluid.

7. An apparatus according to claim 6 further characterized in that said means for collecting and removing cooler fluid comprise:

A. an arcuate tubular conduit disposed within the outermost toroidal chamber against the outermost peripheral wall thereof, one end of said conduit toward the direction of rotation of the disc being open, and

B. a generally radial tubular conduit connected to the opposite end of said arcuate tubular conduit and extending through the toroidal chambers to communicate with the discharge port means in the hub for passage of fluid therethrough.

8. An apparatus according to claim 6 further characterized in that:

A. said entry port means and discharge port means in said hub are disposed generally on opposite sides of the hub,

B. each port interconnecting one of said chambers with another is disposed generally on the opposite side of the chamber from the fluid entry port to that chamber for maximum 'circulaton of fluid through said chambers.

9. A disc heating element for use in a rotary drying apparatus, said disc comprising:

A. a hub,

B. a pair of facing thin-walled circular heat conducting plates mounted on said hub, said plates having a plurality of concentric rings of convex arcuate cross section enclosing a plurality of concentric generally toroidal chambers,

C. entry port means in said hub for introducing heat- .ing fluid to the innermost of said chambers,

D. discharge port means in said hub for withdrawing cooler fluid from the outermost of said chambers,

E. ports interconnecting adjacent chambers for passage of fluid from the innermost chamber of a pair to the next outermost chamber,

F. collector means wihin the outermost of said chambers for collecting cooler fluid therefrom, and

G. conduit means connected to said collecting means and discharge port means for removing cooler fluid.

10. A disc according to claim 9 further characterized in that said fluid collecting and removing means comprises:

A. an arcuate tubular conduit disposed within the outermost toroidal chamber against the outermost peripheral wall thereof, one end of said conduit toward the direction of rotation of the disc being open, and

B. a generally radial tubular conduit connected to the opposite end of said arcuate tubular conduit and extending through the toroidal chambers to communicate with the discharge port means in the hub through said chambers.

r 1 3 UNITED sTATEs PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,777,810 Dated December 1973 lnventm-(s) David L Phillips It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 25, aft'e'r"'dis"', 'ri'ng should be inserted.

signed and sealed this 16th day of April 1971;.

(SEAL) Attest:

EDWARD MJLETCHERJRQ C." MARSHALL 'DANN Attesting Officer Commissioner of Patents 

1. An apparatus for drying solid materials comprising: A. a horizontally disposed housing having a material inlet adjacent one end and a material discharge adjacent the other end, B. a rotor shaft extending longitudinally through said housing journaled for rotation on a horizontal axis, C. a plurality of hollow disc heating elements carried on said shaft for rotation therewith within the housing, D. at leat two chambers within said disc heating elements spaced radially outwardly from said shaft, E. port means interconnecting adjacent chambers for passage of heating fluid, F. first conduit means within said shaft for introducing heating fluid to said heating elements and further conduit means for withdrawing cooler fluid therefrom, and G. means connecting the innermost of said disc chambers with said first conduit means within the shaft and means connecting the outermost of said disc chambers with said further conduit means.
 2. An apparatus according to claim 1 further characterized in that each of said disc heAting elements comprises: A. a housing having a pair of facing thin-walled circular plates having a plurality of concentric rings of convex arcuate cross section enclosing a plurality of concentric generally toroidal chambers, B. collector means within the outermost of said chambers for collecting cooler fluid therefrom and conduit means for removing the same.
 3. An apparatus according to claim 2 further characterized in that: A. said rotor shaft includes a pair of concentric tubes, B. the space between said tubes is a conduit for introducing heating fluid to the disc heating elements and the space within the innermost tube is a return conduit for cooler fluid, C. ports in the outermost tube communicate with the innermost of said concentric toroidal chambers, and D. tubular conduits extending through the walls of both concentric tubes communicate with the fluid collecting and removing means of the outermost disc chamber.
 4. An apparatus according to claim 2 further characterized in that said fluid collecting and removing means connecting the outermost of said disc chambers with said further conduit means comprises: A. an arcuate tubular conduit disposed within the outermost toroidal chamber against the outermost peripheral wall thereof, one end of said conduit toward the direction of rotation of the disc being open, and B. a generally radial tubular conduit connected to the opposite end of said tubular conduit and extending through the toroidal chambers to communicate with the further conduit means of the rotor shaft for the passage of fluid therethrough.
 5. An apparatus according to claim 1 further characterized in that: A. said housing is double-walled over at least part of its surface, and B. inlet and outlet means are provided in communication with the space between said walls for circulation of heating fluid therein.
 6. An apparatus according to claim 1 further characterized in that: A. said rotor shaft includes a pair of concentric tubes, B. the space between said tubes is a conduit for entry of heating fluid and the space within the innermost tube is a return conduit for cooler fluid, C. each disc heating element comprises a hub carrying a pair of facing thin-walled circular heat conducting plates, said plates having a plurality of concentric rings of convex arcuate cross section enclosing a plurality of concentric generally toroidal chambers, D. entry port means in the outermost tube of the rotor shaft communicate with entry port means in said hub, E. collector means are provided within the outermost chamber for collecting cooler fluid, F. conduit means are provided connected to said collector means for removing cooler fluid, and G. tubular conduits extending through the walls of both concentric tubes of the rotor shaft communicate with discharge port means in said hub for removing cooler fluid.
 7. An apparatus according to claim 6 further characterized in that said means for collecting and removing cooler fluid comprise: A. an arcuate tubular conduit disposed within the outermost toroidal chamber against the outermost peripheral wall thereof, one end of said conduit toward the direction of rotation of the disc being open, and B. a generally radial tubular conduit connected to the opposite end of said arcuate tubular conduit and extending through the toroidal chambers to communicate with the discharge port means in the hub for passage of fluid therethrough.
 8. An apparatus according to claim 6 further characterized in that: A. said entry port means and discharge port means in said hub are disposed generally on opposite sides of the hub, B. each port interconnecting one of said chambers with another is disposed generally on the opposite side of the chamber from the fluid entry port to that chamber for maximum circulaton of fluid through said chambers.
 9. A disc heating element for use in a rotary drying aPparatus, said disc comprising: A. a hub, B. a pair of facing thin-walled circular heat conducting plates mounted on said hub, said plates having a plurality of concentric rings of convex arcuate cross section enclosing a plurality of concentric generally toroidal chambers, C. entry port means in said hub for introducing heating fluid to the innermost of said chambers, D. discharge port means in said hub for withdrawing cooler fluid from the outermost of said chambers, E. ports interconnecting adjacent chambers for passage of fluid from the innermost chamber of a pair to the next outermost chamber, F. collector means wihin the outermost of said chambers for collecting cooler fluid therefrom, and G. conduit means connected to said collecting means and discharge port means for removing cooler fluid.
 10. A disc according to claim 9 further characterized in that said fluid collecting and removing means comprises: A. an arcuate tubular conduit disposed within the outermost toroidal chamber against the outermost peripheral wall thereof, one end of said conduit toward the direction of rotation of the disc being open, and B. a generally radial tubular conduit connected to the opposite end of said arcuate tubular conduit and extending through the toroidal chambers to communicate with the discharge port means in the hub for passage of fluid therethrough.
 11. A disc according to claim 9 further characterized in that: A. said entry port means and discharge port means in said hub are disposed generally on opposite sides of the hub, B. each port interconnecting one of said chambers with another is disposed generally on the opposite side of the chamber from the fluid entry port to that chamber for maximum circulation of fluid through said chambers. 